The present invention relates to an apparatus for curing a liner of a pipeline, a method of curing a liner of a pipeline and a system or set of apparatuses for curing a liner of a pipeline.
When pipelines or generally lines or pipe systems, such as sewers or pipelines connected to sewers are to be renovated, trenchless methods have been developed throughout the last three or four decades involving the use lining tubes. In for instance leaky, worn or poorly maintained pipelines, such as sewer pipes, renovation is carried out nowadays by applying lining tubes inside the pipelines. The renovation is carried out in order to avoid infiltration and leakage that can be damaging to the environment. The task in renovating pipelines is to execute preventive maintenance and to perform accurate repairs to prevent further damage, e.g. seeping out of fluids. The renovation of pipelines by the use of liners may advantageously be used in underground pipe systems, e.g. renovating sewers and/or manholes.
The renovation by using pipelines can also take place above ground level, e.g. for renovating vertical pipes, such as process pipes, downpipes, vent ducts etc., such as vertical pipes and duct systems for housing associations in public buildings or in private houses.
The main advantage by using trenchless rehabilitation techniques including the introduction of a liner into a pipeline and curing the liner relates to the fact that the rehabilitation takes places from the inside of the pipeline eliminating the need to obtain access to the pipeline from the outside and the technique therefore involves a minimum work as compared to techniques necessitating digging a hole for obtaining access to the pipeline from the outside and further involves a minimum of inconvenience to the traffic production business and residence.
The technique of rehabilitating an underground pipe by introducing a lining tube impregnated by means of a resin into the pipe and causing the lining tube to be contacted to the inner surface of the pipe by applying pressure to the inside of the lining tube and at the same time applying heat to the lining tube for curing the resin and consequently solidifying the lining tube has been refined for many years. The technique of rehabilitating pipes by introducing a lining tube into the pipe and solidifying the pipe by curing the resin included in the lining tube has been carried out in accordance with two alternative techniques, the one including the simple technique of pulling the lining tube into the pipe to be renovated and forcing the lining tube outwardly into contact with the inner surface of the pipe and a different technique involving the so-called inversion of the lining tube as the lining tube is turned inside out as water or preferably pressurised air is used to force the lining tube in the inversion process into the pipe and afterwards solidifying the lining tube by introducing hot water or steam into the lining tube for causing the resin to cure.
A number of patent applications and patents describe the technique of renovating pipelines by using liners, some of which describe the so-called inversion technique. Others describe technique, in which the liner is simply pulled into the pipeline, e.g. described in WO 2004/104469 and the technique of solidifying or curing the resin has predominantly involved the use of hot water or hot steam for resins being thermal setting resins.
For more than one decade a further technique has been used involving curing the resin of the liner, which resin is cured by exposure to UV radiation by introducing a UV radiation source into the pipeline and curing the resin by using the UV radiating device. The technique of using UV radiation is, however, from several points of view highly disadvantageous although the technique minimises the use of energy as compared to the conventional technique of curing by using hot water or hot steam. Still, UV radiation as such is invisible to the workers or operators performing the work and extremely hazardous to the workers or operators and therefore, on the one hand a simple technical monitoring whether or not the device is operating is not available and, on the other hand the emission from the UV radiating device may cause extreme harm to the workers or operators since UV radiation is known to be cancerogenic. In addition, the known UV radiating devices are based on fairly old-fashioned vacuum tube technology and are therefore firstly fairly unstable and secondly the energy or power generated by the UV radiating device is varying during the short lifetime of the UV radiating device making the utilisation of the UV radiating devices fairly disadvantageous.
Recently the company DSM, NL, has developed and presented a novel photo-curable resin composition, which resin is curable by exposure to visible light in particular light of a wavelength of approximately 450 nm, i.e. blue light. The commercially available photo-curable resin is described in published Dutch patent 1007205, which is also referred to in published international patent application WO2005/103121 filed in the name of the above-mentioned company, which published international patent application refers to different prior art techniques and describes a advantageous photo-curing feature. Reference is made to the above-mentioned patent applications and patents.